In recent years, in an image forming apparatus using an electrophotography, it has been required an electrostatic latent image developing toner (hereafter, it is also simply called as “a toner”) which is thermally fixed at a low temperature. As a toner provided with this property, it is necessary to decrease a melting temperature and a melting viscosity of a binder resin.
For this, it was proposed a toner achieving a low temperature fixability by adding a crystalline resin such as a crystalline polyester resin as a plasticizer (a fixing auxiliary agent) (refer to Patent document 1: JP-A 2015-45850 and Patent document 2: JP-A 2012-168505, for example).
However, when a toner contains a crystalline resin as described, the toner has a problem of having a low thermal stability. In particular, when the toner is kept at high-temperature and high-humidity conditions for a long period of time, bleed out of the releasing agent may occur. This may produce a problem of contaminating the development sleeve or the photoreceptor producing to produce an image noise.